The present invention relates to a mobile object tracking system, and in particular to a mobile radio transmitter which is loaded on a traveling object and transmits high-frequency signals to convey information about a temporary location of the mobile object to a control station.
In general, a conventional mobile object tracking system is comprised of a predetermined number of base stations and mobile radio transmitters for transmitting information about the location of the traveling object, the mobile radio transmitter being loaded on the traveling object. Then, the base stations receive the high-frequency signal transmitted from the mobile radio transmitter and are able to trace the situation of movement of the traveling object.
Besides, the mobile object tracking system traces the traveling situation of the mobile object by dividing a predetermined frequency band into a plurality of frequency bands to assign them to a number of mobile radio transmitters and then receiving the high-frequency signal in the assigned frequency band from the mobile object in order to trace and observe a single mobile object. Therefore, the mobile radio transmitter transmits either the high-frequency signal for confirming the location in response to a presence of the received high-frequency signal from the control station in traveling, or the high frequency signal for confirming the location unilaterally.
However, since said mobile object tracking system uses the high-frequency signal of the assigned frequency band by dividing a predetermined frequency band, mutual interference phenomenon arises between frequencies that each mobile radio transmitter uses, and it is liable to interrupt the mobile object tracking operation due to the influence of the high-frequency signal generated by a third party. Therefore, there has been a problem that the tracing of only a limited number of mobile object is possible because the predetermined frequency band is divided into a plurality of frequency bands and assigned to each corresponding radio transmitter.